Preheat oven to 350 degrees and spray loaf pans with non-stick cooking spray.
Make sure you are using 8x4x2.5 inch loaf pans, as this recipe will make two bread loaves. You will fill each pan with about 4 cups of mixture. If using a large, 11 inch loaf pan, you will make only one loaf.
Mix together dry cake mix, pumpkin, egg whites, vanilla extract, cinnamon and pumpkin pie spice.
Fold in chopped walnuts to mixture and stir.
Transfer batter evenly into the two loaf pans.
Bake for 35-40 minutes until toothpick inserted into center comes out clean.